What foundries have to know about 3D-printing

3D printing technology is moving ahead by leaps and bounds. Whether foundries use sand molds for metal casting or plastic melt-off models for investment casting, in both cases they benefit from the many advantages of additive 3D printing processes.

For many years now, many foundries have regarded sand casting molds and cores produced with a 3D printer as the standard. This technology is well established in the iron and metal casting field and is used wherever it is beneficial. While these applications primarily lie in the area of prototypes and small batches, the limits are increasingly shifting toward bigger and bigger volumes, as the performance of the 3D printing systems continues to improve.

In terms of overall costs, 3D printing is always the more economical alternative to conventional processes up to a certain batch size, since tool costs are eliminated. The smaller the batch size, the greater the cost advantage offered by voxeljet’s technology. With complex geometries in particular, 3D printing is the most economical choice, even in batch sizes of several hundred units, although it cannot replace classic mold construction in large series.

Combination of 3D-printed cores and classic mold construction

Whenever suitable, innovative foundries today rely on a combination of 3D-printed cores and molds produced with conventional methods. This approach is a good choice, among other things when producing complex cores with undercuts, which are required for impellers, for instance. The cores can be printed in the 3D printer and subsequently integrated into the conventional mold. The benefits include a smaller number of parts and a much less laborious mold construction process, since the method eliminates the time-consuming, conventional production and assembly of the complex cores and also minimizes subsequent remachining.

High-precision melt-off models for investment casting

In addition to printing sand molds, more and more foundries also rely on models produced with the 3D printer for investment casting. This method facilitates the easy and straightforward production of wax models. Even though these models are no longer made from wax, but rather from plastic, this does not have any bearing on the subsequent process steps. The production of PMMA models in 3D printers is easy enough: they are printed exactly according to CAD data. To increase the quality of the melt-off process, the plastic models are also infiltrated with wax, which creates a particularly fine-pored and homogeneous surface.

Arrangement of 780 two-stroke engines in the VX1000 from voxeljet

Case studies

A wide range of applications, such as rapid manufacturing of two-stroke motors for chainsaws, demonstrates the performance of voxeljet printers in practice. One motor is just 78 x 76 x 59 millimeters in size. To produce the models as quickly and economically as possible, voxeljet combined 780 of these motors into a single print job in a build space whose dimensions were 1,000 x 600 x 500 millimeters. It took 23 hours to print the motors with the VX1000 high-performance printer, which corresponds to a print time of only 1.8 minutes per motor.

Further Case Studies


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